10,667 research outputs found
Multi-Resolution Video Streaming in Peer-to-peer Networks
We consider multi-resolution streaming in fully-connected peer-to-peer
networks, where transmission rates are constrained by arbitrarily specified
upload capacities of the source and peers. We fully characterize the capacity
region of rate vectors achievable with arbitrary coding, where an achievable
rate vector describes a vector of throughputs of the different resolutions that
can be supported by the network. We then prove that all rate vectors in the
capacity region can be achieved using pure routing strategies. This shows that
coding has no capacity advantage over routing in this scenario
Multi-View Video Packet Scheduling
In multiview applications, multiple cameras acquire the same scene from
different viewpoints and generally produce correlated video streams. This
results in large amounts of highly redundant data. In order to save resources,
it is critical to handle properly this correlation during encoding and
transmission of the multiview data. In this work, we propose a
correlation-aware packet scheduling algorithm for multi-camera networks, where
information from all cameras are transmitted over a bottleneck channel to
clients that reconstruct the multiview images. The scheduling algorithm relies
on a new rate-distortion model that captures the importance of each view in the
scene reconstruction. We propose a problem formulation for the optimization of
the packet scheduling policies, which adapt to variations in the scene content.
Then, we design a low complexity scheduling algorithm based on a trellis search
that selects the subset of candidate packets to be transmitted towards
effective multiview reconstruction at clients. Extensive simulation results
confirm the gain of our scheduling algorithm when inter-source correlation
information is used in the scheduler, compared to scheduling policies with no
information about the correlation or non-adaptive scheduling policies. We
finally show that increasing the optimization horizon in the packet scheduling
algorithm improves the transmission performance, especially in scenarios where
the level of correlation rapidly varies with time
Network coding for transport protocols
With the proliferation of smart devices that require Internet connectivity anytime, anywhere, and the recent technological
advances that make it possible, current networked systems will have to provide a various range of services, such as content
distribution, in a wide range of settings, including wireless environments. Wireless links may experience temporary losses,
however, TCP, the de facto protocol for robust unicast communications, reacts by reducing the congestion window drastically
and injecting less traffic in the network. Consequently the wireless links are underutilized and the overall performance of the
TCP protocol in wireless environments is poor. As content delivery (i.e. multicasting) services, such as BBC iPlayer, become
popular, the network needs to support the reliable transport of the data at high rates, and with specific delay constraints. A
typical approach to deliver content in a scalable way is to rely on peer-to-peer technology (used by BitTorrent, Spotify and
PPLive), where users share their resources, including bandwidth, storage space, and processing power. Still, these systems
suffer from the lack of incentives for resource sharing and cooperation, and this problem is exacerbated in the presence of
heterogenous users, where a tit-for-tat scheme is difficult to implement.
Due to the issues highlighted above, current network architectures need to be changed in order to accommodate the usersÂż
demands for reliable and quality communications. In other words, the emergent need for advanced modes of information
transport requires revisiting and improving network components at various levels of the network stack.
The innovative paradigm of network coding has been shown as a promising technique to change the design of networked
systems, by providing a shift from how data flows traditionally move through the network. This shift implies that data flows are
no longer kept separate, according to the Âżstore-and-forwardÂż model, but they are also processed and mixed in the network. By
appropriately combining data by means of network coding, it is expected to obtain significant benefits in several areas of
network design and architecture.
In this thesis, we set out to show the benefits of including network coding into three communication paradigms, namely point-topoint
communications (e.g. unicast), point-to-multipoint communications (e.g. multicast), and multipoint-to-multipoint
communications (e.g. peer-to-peer networks). For the first direction, we propose a network coding-based multipath scheme and
show that TCP unicast sessions are feasible in highly volatile wireless environments. For point-to-multipoint communications,
we give an algorithm to optimally achieve all the rate pairs from the rate region in the case of degraded multicast over the
combination network. We also propose a system for live streaming that ensures reliability and quality of service to heterogenous
users, even if data transmissions occur over lossy wireless links. Finally, for multipoint-to-multipoint communications, we design
a system to provide incentives for live streaming in a peer-to-peer setting, where users have subscribed to different levels of
quality.
Our work shows that network coding enables a reliable transport of data, even in highly volatile environments, or in delay
sensitive scenarios such as live streaming, and facilitates the implementation of an efficient incentive system, even in the
presence of heterogenous users. Thus, network coding can solve the challenges faced by next generation networks
in order to support advanced information transport.Postprint (published version
Network coding meets multimedia: a review
While every network node only relays messages in a traditional communication system, the recent network coding (NC) paradigm proposes to implement simple in-network processing with packet combinations in the nodes. NC extends the concept of "encoding" a message beyond source coding (for compression) and channel coding (for protection against errors and losses). It has been shown to increase network throughput compared to traditional networks implementation, to reduce delay and to provide robustness to transmission errors and network dynamics. These features are so appealing for multimedia applications that they have spurred a large research effort towards the development of multimedia-specific NC techniques. This paper reviews the recent work in NC for multimedia applications and focuses on the techniques that fill the gap between NC theory and practical applications. It outlines the benefits of NC and presents the open challenges in this area. The paper initially focuses on multimedia-specific aspects of network coding, in particular delay, in-network error control, and mediaspecific error control. These aspects permit to handle varying network conditions as well as client heterogeneity, which are critical to the design and deployment of multimedia systems. After introducing these general concepts, the paper reviews in detail two applications that lend themselves naturally to NC via the cooperation and broadcast models, namely peer-to-peer multimedia streaming and wireless networkin
In-Network View Synthesis for Interactive Multiview Video Systems
To enable Interactive multiview video systems with a minimum view-switching
delay, multiple camera views are sent to the users, which are used as reference
images to synthesize additional virtual views via depth-image-based rendering.
In practice, bandwidth constraints may however restrict the number of reference
views sent to clients per time unit, which may in turn limit the quality of the
synthesized viewpoints. We argue that the reference view selection should
ideally be performed close to the users, and we study the problem of in-network
reference view synthesis such that the navigation quality is maximized at the
clients. We consider a distributed cloud network architecture where data stored
in a main cloud is delivered to end users with the help of cloudlets, i.e.,
resource-rich proxies close to the users. In order to satisfy last-hop
bandwidth constraints from the cloudlet to the users, a cloudlet re-samples
viewpoints of the 3D scene into a discrete set of views (combination of
received camera views and virtual views synthesized) to be used as reference
for the synthesis of additional virtual views at the client. This in-network
synthesis leads to better viewpoint sampling given a bandwidth constraint
compared to simple selection of camera views, but it may however carry a
distortion penalty in the cloudlet-synthesized reference views. We therefore
cast a new reference view selection problem where the best subset of views is
defined as the one minimizing the distortion over a view navigation window
defined by the user under some transmission bandwidth constraints. We show that
the view selection problem is NP-hard, and propose an effective polynomial time
algorithm using dynamic programming to solve the optimization problem.
Simulation results finally confirm the performance gain offered by virtual view
synthesis in the network
A Survey on Adaptive Multimedia Streaming
Internet was primarily designed for one to one applications like electronic mail, reliable file transfer etc. However, the technological growth in both hardware and software industry have written in unprecedented success story of the growth of Internet and have paved the paths of modern digital evolution. In today’s world, the internet has become the way of life and has penetrated in its every domain. It is nearly impossible to list the applications which make use of internet in this era however, all these applications are data intensive and data may be textual, audio or visual requiring improved techniques to deal with these. Multimedia applications are one of them and have witnessed unprecedented growth in last few years. A predominance of that is by virtue of different video streaming applications in daily life like games, education, entertainment, security etc. Due to the huge demand of multimedia applications, heterogeneity of demands and limited resource availability there is a dire need of adaptive multimedia streaming. This chapter provides the detail discussion over different adaptive multimedia streaming mechanism over peer to peer network
Survey of End-to-End Mobile Network Measurement Testbeds, Tools, and Services
Mobile (cellular) networks enable innovation, but can also stifle it and lead
to user frustration when network performance falls below expectations. As
mobile networks become the predominant method of Internet access, developer,
research, network operator, and regulatory communities have taken an increased
interest in measuring end-to-end mobile network performance to, among other
goals, minimize negative impact on application responsiveness. In this survey
we examine current approaches to end-to-end mobile network performance
measurement, diagnosis, and application prototyping. We compare available tools
and their shortcomings with respect to the needs of researchers, developers,
regulators, and the public. We intend for this survey to provide a
comprehensive view of currently active efforts and some auspicious directions
for future work in mobile network measurement and mobile application
performance evaluation.Comment: Submitted to IEEE Communications Surveys and Tutorials. arXiv does
not format the URL references correctly. For a correctly formatted version of
this paper go to
http://www.cs.montana.edu/mwittie/publications/Goel14Survey.pd
Multimedia Social Networks: Game Theoretic Modeling and Equilibrium Analysis
Multimedia content sharing and distribution over multimedia social networks is more popular now than ever before: we download music from Napster, share our images on Flickr, view user-created video on YouTube, and watch peer-to-peer television using Coolstreaming, PPLive and PPStream. Within these multimedia social networks, users share, exchange, and compete for scarce resources such as multimedia data and bandwidth, and thus influence each other's decision and performance. Therefore, to provide fundamental guidelines for the better system design, it is important to analyze the users' behaviors and interactions in a multimedia social network, i.e., how users interact with and respond to each other.
Game theory is a mathematical tool that analyzes the strategic interactions among multiple decision makers. It is ideal and essential for studying, analyzing, and modeling the users' behaviors and interactions in social networking. In this thesis, game theory will be used to model users' behaviors in social networks and analyze the corresponding equilibria. Specifically, in this thesis, we first illustrate how to use game theory to analyze and model users' behaviors in multimedia social networks by discussing the following three different scenarios. In the first scenario, we consider a non-cooperative multimedia social network where users in the social network compete for the same resource. We use multiuser rate allocation social network as an example for this scenario. In the second scenario, we consider a cooperative multimedia social network where users in the social network cooperate with each other to obtain the content. We use cooperative peer-to-peer streaming social network as an example for this scenario. In the third scenario, we consider how to use the indirect reciprocity game to stimulate cooperation among users. We use the packet forwarding social network as an example.
Moreover, the concept of ``multimedia social networks" can be applied into the field of signal and image processing. If each pixel/sample is treated as a user, then the whole image/signal can be regarded as a multimedia social network. From such a perspective, we introduce a new paradigm for signal and image processing, and develop generalized and unified frameworks for classical signal and image problems. In this thesis, we use image denoising and image interpolation as examples to illustrate how to use game theory to re-formulate the classical signal and image processing problems
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